>I've been cleaning shells like crazy this month...tons from my
>collecting trip in August :-). I used the freeze-thaw-freeze-thaw
>method on the snails. I found that a small percentage of my
>Nucella lamellosa broke, I presume from the freezing. This
>breakage consisted of large sections of the whorls cracked off
>so that there are big holes in the shells. I have many hundreds
>of Nucella lamellosa, so this isn't so bad, except that one of
>the broken ones turned out to be my nicest bright purple
>specimen...grrr!

YES!!

Astraea heliotropium is a dead loss if frozen (or boiled); the
umbilical wall decorticates and other bits can drop off too.
Amphibola crenata falls apart, especially around the umbilicus also.

The problem is probably not water but differential thermal expansion
in parts of the shell varying in thickness, I suspect, which could
explain why the breaks occur in the more solid parts of the shell.

If you don't want that broken purple N. lamellosa... I've never seen
a purple one... send it to me! (with all the bits) I'm not averse to
scarred specimens.

>In some cases freezing isn't the solution - but one must try to see what
>happens. I had some shells cracked the same way - some bivalves with
>lamellae, some landnails and the worse was two Pleurotomaria... their top
>just came off!

Marcus, you can send me those Perotrochus too, please!!

>When I travel I use alcohol which is the easiest way. Sometimes it is not so
>good to use it in small Marginellas or any other transparent shell since you
>don't want any animal left inside.
>The problem is that in some Countries you don't find alcohol to use. The
>solution is...Vodka, aguardiente, or similar spirit drink. I had to use
>Aguardiente in Ecuador since I could not find alcohol. Of course the hotel's
>maid were looking weird at us every time she had to clean the room and had
>to pick several empty bottles....

Ethanol (and other alcohols), I believe, do not fix tissues well, and
if allowed to evaporate away the tissues are free to rot. Supposedly
formaldehyde denatures the proteins and will prevent decomposition on
loss of the preservative. If your country's Customs people are leery
of allowing in tissues, they will allow formalin-fixed (let 'em sniff
it!) tissues into the country, while they might not allow
ethanol-fixed specimens in. NZ's Customs is paranoid about allowing
any tissues in, but gave no trouble when told they were
formalin-fixed.

Take BUFFERED formalin on trips to avoid trying to find it
on-location. Unbuffered formalin contains formic acid, which may
affect shell surfaces if left in for many days (I use unbuffered 4%
formalin solution overnight to fix bulk dredged micro samples, and
have no damage occurring).

>I've found that alcohol hardens the animal somewhat, making it far
>more difficult to get the last bits out of the shell...but then those last
>bits are more likely to dry without rotting and smelling bad, so it's
>a trade-off.

I use 4% formalin overnight to stiffen the animal's muscle tissues
just enough to enable hooking out with a probe. Ethanol will work
too, but is expensive. Formalin is cheap in bulk and a 20-liter
container of agricultural-grade will dilute to 4%, meaning one
container will last a lifetime.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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Seashell, Macintosh, VW/Toyota van nut